Characterizing the performance of Flash memory storage devices and its impact on algorithm design

Initially used in digital audio players, digital cameras, mobile phones, and USB memory sticks, flash memory may become the dominant form of end-user storage in mobile computing, either completely replacing the magnetic hard disks or being an additional secondary storage. We study the design of algorithms and data structures that can exploit the flash memory devices better. For this, we characterize the performance of NAND flash based storage devices, including many solid state disks. We show that these devices have better random read performance than hard disks, but much worse random write performance. We also analyze the effect of misalignments, aging and past I/O patterns etc. on the performance obtained on these devices. We show that despite the similarities between flash memory and RAM (fast random reads) and between flash disk and hard disk (both are block based devices), the algorithms designed in the RAM model or the external memory model do not realize the full potential of the flash memory devices. We later give some broad guidelines for designing algorithms which can exploit the comparative advantages of both a flash memory device and a hard disk, when used together

Untersuchung von Faktoren, welche die mikrobiologische Konjunktivalflora von Hornhautspendern nach Desinfektion mit Povidon-Jod und die Kontamination des Organkulturmediums beeinflussen

Weltweit, so wie auch in Deutschland, ist die Hornhauttransplantation die meistdurchgeführte Gewebetransplantation am Menschen. Sie wird am häufigsten zur Behandlung von Patienten mit Fuchs´scher Endotheldystrophie oder Keratokonus verwendet und kann zu einer erheblichen Verbesserung des Sehvermögens und der Lebensqualität beitragen. Trotz 7000 Eingriffen pro Jahr in Deutschland besteht aktuell ein Mangel an Spenderhornhäuten. Ziel der Studie war es, die Frage zu klären, ob eine Korrelation zwischen der mikrobiellen Kontamination des Organkulturmediums und positiven Bindehautabstrichen der Hornhautspender nach Desinfektion mit Povidon-Jod besteht und ob es Faktoren gibt, die in Zusammenhang mit der Besiedlung stehen. Hierfür wurden retrospektiv Daten von 1008 Bindehautabstrichen von 252 Hornhautspendern analysiert, die zwischen Juli 2015 und September 2017 in die Hornhautdatenbank der Tübinger Universitäts-Augenklinik aufgenommen worden waren. Die Positivrate der Bindehautabstriche lag bei 28.4 %, am häufigsten verursacht durch Keime der physiologischen Standortflora der Konjunktiva, während die Rate kontaminierter Organkulturmedien unter Einbeziehung all der Medien, zu denen ein mikrobiologisches Ergebnis vorlag, bei 1.0 % lag. Es konnte kein signifikanter Zusammenhang zwischen dem Ergebnis der Bindehautabstriche und einer Kontamination des Kulturmediums festgestellt werden (p = 0.08). Das Risiko für positive Bindehautabstriche wurde signifikant erhöht durch Hospitalisationszeiten von 2 bis 7 Tagen im Vergleich zu Zeiten von < 2 Tagen (p = 0.021), Karzinom (p = 0.007), Metastasen (p = 0.016), Zeitspannen zwischen Tod und Entnahme der Bindehautabstriche von ≥ 6 bis 72 Stunden (p = 0.007), die Entnahme in Kühlräumen oder der Pathologie des Tübinger Universitäts-klinikums (p = 0.014) oder in externen Räumlichkeiten (p = 0.003) gegenüber der Entnahme auf Intensivstationen des Tübinger Universitätsklinikums. 87 Dem hingegen hatten die Faktoren Alter (p = 0.16 und p = 0.08), Geschlecht (p = 0.39), Todesursache (0.16 ≤ p ≤ 0.73), septischer Spender (p = 0.23), Diabetes mellitus (p = 0.08), Chemotherapie (p = 0.54), Infektionen (p = 0.40), Multiorganspender (p = 0.47), die Anzahl enukleierender Ärzte (p = 0.23) und die Temperatur im Monat der Spende (p = 0.92) keinen signifikanten Einfluss auf die Positivrate der Bindehautabstriche. Keiner der untersuchten Faktoren übte einen signifikanten Einfluss auf die Kontaminationsrate der Organkulturmedien aus. Während die Positivrate und das Erregerspektrum der Bindehautabstriche im Einklang mit Ergebnissen anderer Studien stehen, können Gründe für die im Vergleich zu anderen Studien geringe Kontaminationsrate der Kulturmedien im ausführlichen Dekontaminationsprotokoll gesehen werden. Um künftig dem Mangel an Hornhäuten entgegenzuwirken, kann über den Einsatz weiterer antimikrobieller Substanzen zum Kulturmedium und Schritte zur zeitlichen Prozessoptimierung des Ablaufs einer Spende diskutiert werden. Darüber hinaus findet aktuell eine Weiterentwicklung von Methoden statt, die künftig durch zellbasierte Ansätze, Biokorneas und neue Therapien den Bedarf an Spenderhornhäuten verringern können

The role of CD44v6 in RTK internalization and trafficking

Internalization of receptor tyrosine kinases (RTKs) is crucial for RTK signaling and cellular responses such as cell migration. This work shows that CD44v6 mediates the internalization of the RTK Met and traffics together with Met through endosomal compartments suggesting that CD44v6 is required for Met-signaling from endosomes. The RTK VEGFR-2 also interacts with CD44v6. However Met and VEGFR-2 are activated with strikingly different kinetics suggesting a different mechanism of internalization

Absence of the Septum Pellucidum Associated with a Midline Fornical Nodule and Ventriculomegaly: A Report of Two Cases

We report two autopsy cases that revealed the partial absence of the septum pellucidum with ventriculomegaly. In each case, the brain showed mild dilatation of both frontal horns of the lateral ventricles, normal third and fourth ventricles and no aqueductal stenosis. The posterior portion of the septum pellucidum was absent and the fornices were fused in a single midline nodule, abnormally displaced to a caudal position and lodged in the foramina of Monro. The brain base showed no apparent abnormalities; the optic nerves were well developed. We conclude that the caudally displaced fornix in the absence of the septum pellucidum may have intermittently obstructed the foramina of Monro and induced mild ventriculomegaly

Tumor Necrosis Factor Alpha-Induced Recruitment of Inflammatory Mononuclear Cells Leads to Inflammation and Altered Brain Development in Murine Cytomegalovirus-Infected Newborn Mice

Congenital human cytomegalovirus (HCMV) infection is a significant cause of abnormal neurodevelopment and long-term neurological sequelae in infants and children. Resident cell populations of the developing brain have been suggested to be more susceptible to virus-induced cytopathology, a pathway thought to contribute to the clinical outcomes following intrauterine HCMV infection. However, recent findings in a newborn mouse model of the infection in the developing brain have indicated that elevated levels of proinflammatory mediators leading to mononuclear cell activation and recruitment could underlie the abnormal neurodevelopment. In this study, we demonstrate that treatment with tumor necrosis factor alpha (TNF-α)-neutralizing antibodies decreased the frequency of CD45+ Ly6Chi CD11b+ CCR2+ activated myeloid mononuclear cells (MMCs) and the levels of proinflammatory cytokines in the blood and the brains of murine CMV-infected mice. This treatment also normalized neurodevelopment in infected mice without significantly impacting the level of virus replication. These results indicate that TNF-α is a major component of the inflammatory response associated with altered neurodevelopment that follows murine CMV infection of the developing brain and that a subset of peripheral blood myeloid mononuclear cells represent a key effector cell population in this model of virus-induced inflammatory disease of the developing brain

A systematic review and meta-analysis to determine the contribution of mr imaging to the diagnosis of foetal brain abnormalities In Utero.

OBJECTIVES: This systematic review was undertaken to define the diagnostic performance of in utero MR (iuMR) imaging when attempting to confirm, exclude or provide additional information compared with the information provided by prenatal ultrasound scans (USS) when there is a suspicion of foetal brain abnormality. METHODS: Electronic databases were searched as well as relevant journals and conference proceedings. Reference lists of applicable studies were also explored. Data extraction was conducted by two reviewers independently to identify relevant studies for inclusion in the review. Inclusion criteria were original research that reported the findings of prenatal USS and iuMR imaging and findings in terms of accuracy as judged by an outcome reference diagnosis for foetal brain abnormalities. RESULTS: 34 studies met the inclusion criteria which allowed diagnostic accuracy to be calculated in 959 cases, all of which had an outcome reference diagnosis determined by postnatal imaging, surgery or autopsy. iuMR imaging gave the correct diagnosis in 91 % which was an increase of 16 % above that achieved by USS alone. CONCLUSION: iuMR imaging makes a significant contribution to the diagnosis of foetal brain abnormalities, increasing the diagnostic accuracy achievable by USS alone. KEY POINTS: • Ultrasound is the primary modality for monitoring foetal brain development during pregnancy • iuMRI used together with ultrasound is more accurate for detecting foetal brain abnormalities • iuMR imaging is most helpful for detecting midline brain abnormalities • The moderate heterogeneity of reviewed studies may compromise findings

Assessing the life cycle environmental impacts of titania nanoparticle production by continuous flow solvo/hydrothermal synthesis

Continuous-flow hydrothermal and solvothermal syntheses offer substantial advantages over conventional processes, producing high quality materials from a wide range of precursors. In this study, we evaluate the “cradle-to-gate” life cycle environmental impacts of alternative titanium dioxide (TiO₂) nanoparticle production parameters, considering a range of operational conditions, precursors, material properties and production capacities. A detailed characterisation of the nano-TiO₂ products allows us, for the first time, to link key nanoparticle characteristics to production parameters and environmental impacts, providing a useful foundation for future studies evaluating nano-TiO₂ applications. Five different titanium precursors are considered, ranging from simple inorganic precursors, like titanium oxysulphate (TiOS), to complex organic precursors such as titanium bis(ammonium-lactato)dihydroxide (TiBALD). Synthesis at the laboratory scale is used to determine the yield, size distribution, crystallinity and phase of the nanoparticles. The specifications and operating experience of a full scale plant (>1000 t per year) are used to estimate the mass and energy inputs of industrial scale production for the life cycle assessment. Overall, higher process temperatures are linked to larger, more crystalline nanoparticles and higher conversion rates. Precursor selection also influences nano-TiO₂ properties: production from TiOS results in the largest particle sizes, while TiBALD achieves the smallest particles and narrowest size distribution. Precursor selection is the main factor in determining cradle-to-gate environmental impacts (>80% in some cases), due to the production impact of complex organic precursors. Nano-TiO2 production from TiOS shows the lowest global warming potential (GWP) (<12 kg CO₂-eq. per kg TiO₂) and cumulative energy demand (CED) (<149 MJ kg¯¹ TiO₂) due to the low environmental impact of the precursor, the use of water as a solvent and its high yield even at lower temperatures. Conversely, the TiBALD precursor shows the highest impact (86 kg CO₂-eq. per kg TiO₂ and 1952 MJ kg¯¹ TiO₂) due to the need for additional post-synthesis steps and complexity of precursor manufacturing. The main purpose of this study is not a direct comparison of the environmental impacts of TiO₂ nanoparticles manufactured utilizing various precursors under different conditions, but to provide an essential foundation for future work evaluating potential applications of nano-TiO₂ and their life cycle environmental impacts